Bitcoin Core is not affiliated with the website you downloaded the node installer from - bitsblock.io, and the official Bitcoin Core client does not provide functionality you ask about. I noticed that when you click on download button on this website it takes you to some restore form. This seems very sketchy - I'd never provide online my private key nor any other means to derive it (such as list of backup codes, phrases, passwords, etc.). Try looking for legit wallet that supports BIP39, I cannot vouch for that but supposedly Electrum wallet does that. Also, as mentioned here, it might be actually a restore phrase for blockchain.info online wallet (though as mentioned earlier, I would discourage entering recovery phrases on any website).